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Geerts et al Chest 2008 Timing of Thromboprophylaxis Initiation For patients receiving LMWH as thromboprophylaxis in major orthopedic surgery, we recommend starting either preoperatively or postoperatively (Grade 1A). For patients receiving fondaparinux as thromboprophylaxis in major orthopedic surgery, we recommend starting either 6 to 8 h after surgery or the next day (Grade 1A).

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Geerts et al Chest 2008 Duration of Thromboprophylaxis For patients undergoing THR, TKR, or HFS, we recommend thromboprophylaxis with one of the recommended options for at least 10 days (Grade 1A). We recommend that thromboprophylaxis be extended beyond 10 days and up to 35 days after surgery (Grade 1A THR, Grade 2B TKR, Grade 1A HFS). The recommended options for extended thromboprophylaxis in THR include LMWH, a VKA, or fondaparinux.

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Renal Impairment and Anticoagulant Dosing We recommend that renal function be considered when making decisions about the use and/or the dose of LMWH, fondaparinux, and other antithrombotic drugs that are cleared by the kidneys, particularly in elderly patients, patients with diabetes mellitus, and those at high risk for bleeding (Grade 1A). Depending on the circumstances, we recommend one of the following options in this situation: avoiding the use of an anticoagulant that bioaccumulates in the presence of renal impairment, using a lower dose of the agent, or monitoring the drug level or its anticoagulant effect (Grade 1B). Geerts et al Chest 2008